Regulating mechanism for arc-lamps.



.l. L. HALL. REGULATING MECHANISM FOR ARC LAMPS.

APPLICATION FILED APR. H, 1913. 1,171,945. Patented 'Feb. 15, 1916..

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P v :9 H I 40 Witnesses: inventor 2W6, K John LHali,

His Attorny.

UNITED STATES P TENT-(ounce;

JOHN L. HALL, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

REGULATING MECHANISM FOR ARC-LAMPS. '4

To all whom it may concern:

Be it known that 1, JOHN L. HALL, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Regulating Mechanism for Arc-Lamps, of which the following is a specification.

My invention has reference to an arc lamp, and more particularly to a mechanism for feeding the electrodes, and has for its object an in'iprovementin a device of this character.

In arc lamps it is desirable, and in searchlights it is particularly desirable, that the arc characteristics should remain as nearly constant as possible, as variations in the" arc are attended by corresponding variations in the light emitted by the lamp, and this is a feature which is to be avoided as far as possible.

My invention comprises a motor for feedingthe electrodes together and apart in accordance with the requirements of the are through a speed responsive device, the motor being so arranged with reference to the are as to quickly and surely respond to variations in the are by a corresponding variation in speed.

17 to the other electrode 2.

18 for the motor is connected across the conductors 15 and 17, so that both the armascrew-threaded shafts 5 and 6 provided at. their-inner ends with gears 7 and 8 engaging a third gear9 carried on a shaft 10.

The electrodes are fed together and apart in accordance with the requirements of the are by an electric motor 11 which is energized from a suitable source of energy. One

side of the generator is connected by a con-.

ductor 14 to one of the electrodes 1 through an adjustable resistance 13 and by a conductor 15 to one of the brushes of the armature 16 of the motor. The opposite brush of the armature is connected by a conductor A shunt field Specification of Letters Patent. i Patented Feb Application filed April 11, 1913. Serial No. 760,467.

the arc, and the voltage across their terminals varies with the voltageof the arc,

Now in order to render the speed of the motor sensitive to the action of the are, I proyide the motor with a series field 18 which is connected to the conductor 17 by a linking conductor 19 and by a conductor 20 to the opposite side of the generator 12. The series field is thus qonnected in series with the arc and the object of this series field is to make it possible to increase the total field excitation with a drop of potential across the arc and to decrease the total field excitation with an increase of potential across the are as is more fully hereinafter explained.

A shaft 26 is continuously rotated by the armature of the motor. This shaft is providedwith a worm 27 which engages a worm gear 28 mounted on one end of a shaft 29, the opposite end of which carries a bevel gear 30. This bevel engages ,two

bevel gears 31, each of which is comprised in a differential gearing, and as the two differential gears are counterparts, but one of them will be described. The bevel gear 31 and a second bevel 32 secured thereto are mounted loosely upon the shaft 10. other bevel gear 33 facing the gear 32 is secured to a collar 3-1, which is fastened upon the shaft 10. The bevel 35 of a second differential gear is also secured to the colhr 34:. Two or more planetary gears 36,

mounted within a'ring 37 engage the bevels 32 and 33. The gears 31 are continuously rotating in opposite directions and when gears .36 are free to rotate, the planetary gears merely. rotate about the shaft 10 as an -the two rings 37 carrying the planetary axis without rotating -either of the gears 33 'or 35 or the shaft to which they are se- VVhen, however, movement of either cured. of the rings is prevented, then the planetary gears 36 rotate about their own axes and cause a rotation of the bevel3-3 or 35 :and the shaft 10 in the opposite direction from which the corresponding gear 31 is rotating. Each of the rings 37 is provided with a series of inwardly projecting fingers or teeth 38 which are adapted to be'engaged by an arm 39 pivoted at 40.

The position of the arm 39 is controlled by a governor, the weighted centrifugal arms 42 of which are pivoted at 43 on lugs 41 on the shaft 26. The arms 42 are provided with fingers 44 projecting inardly past the pivots 43 and engaging a disk 46 on'a bar 47 slidably mounted within the enlarged end of the shaft 26. Outward centrifugal movement of the weighted arms 42 is restrained by a spring 45 in the usual manner. The outer end of the bar 47 en-. gages an arm 48 impelled toward the right by' a spring 49. This arm is connected to the arm 39 by means of a link 50. When the arm 39 engages one of theteeth 38 on the ring 37 of the second differential, then the bevel-gear 35 is caused to rotate, but in the opposite direction from that of the gear 33, when the rotation of the ring 37 of the 4 f accordance with the speed of the motor.

The operation of my are lamp is as follows: When the lamp is without current, the electrodes will usually be separated by the distance corresponding to the length of the are which was last formed. Now, when. current is turned on, there will be a maximum potential across the shunt field and armature of the motor, as the drop in the resistance 13 is practically negligible. While the shunt field, however, now receives its maximum excitation, the total excitation is a minimum, as the excitation of the series field which is wound accumulatively with the shunt field is small in comparison to its excitation when the arc is established, and

the field windings are so designed as to cause an increase in the total excitation as the series field increases. The maximum voltage existing at this time across the armature and the :minimum field excitation combine to produce a maximum speed in the motor, with the result that the electrodes are rapidly run together, As soon as the electrodes are brought into engagement, current flows between the electrodes, the series field is excited, with the result that, while the voltage across the shunt field is less than before and the excitation of the shunt field is correspondingly less, the combined excitation of the series and shunt fields is greater than at starting, and the speed of the motor is greatly decreased, due to the increased excitation as well as to the decreased voltage existing across the armatures. It is thus evident that the motor attains its maximum speed at a time wheir the lamp is idle and when it is desirable to bring the electrodes into engagement as quickly as possible, and that when the electrodes are brought into engagement, they are'then separated much less rapidly, there'- by giving the crater of the are time to form and rendering the establishment .of the arc are becomes abnormally high, the voltage across the are becomes correspondingly high, and the current in the arc and in the series field decreases with the result that the field excitation decreases and the armature voltage increases. The speed of the motor is correspondingly increased, the gov ernor forces the arm 48 to the left and the arm 39 into engagementwith one of the teeth 38 of the differential gear at the left, and the shaft 10 is rotated in a direction to feed the electrodes toward each other. If, on the other hand, the electrodes are too close together, the resistance of the arc drops below its normal value, and the voltage across the same decreases. The speed of the motor, therefore, falls below its normal. value, the arm 39 engages one of the teeth at the right, and the shaft 10 is Totated in the direction opposite so that which took place when the resistance of the arc was excessive, and the electrodes are fed apart. I

A lamp made in accordance with my invention 1s, in practice, sensitive to the action of the are, and its regulation is positive and sensitive.

IVhile I have illustrated and described the best embodiment of my invention known to me, it will be understood that numerous modifications could be embodied in-my invention without departing from the spirit thereof. For example, while I have illustrated a double differential gear for reversing-the direction of rotation of the shaft 10, which feeds the electrodes, any equivalent device which is responsive to the speed of the motor could be' used. Furthermore, while I have here illustrated both of the electrodes movable, it might under some circumstances be desirable to make one of the electrodes stationary, and but a single one movable, and when I refer, therefore, .in the claims to means for feeding the electrodes, it will, of course, be understood that they cover a device which feeds but one of the electrodes. In general, I desire it to be understood that I do not intend to limit my invention, except as it is limited by the scope of the claims.

Vhat I claim as new and desire to secure by Letters Patent of the United States, is

connected across the arc, and means for varying the field excitationinversely as th voltage across the arc.

2. In an arc lamp, a pair of cooperating electrodes, a compound motor, speed responsivemeans connected to the motor for feeding the electrodes together or apart in accordance with the speed of the motor, the fields of the motor being accumulatively wound, the series field being connected in series with the arc, and the shunt field and the armature in shunt to the arc.

3. Inan arc lamp, an electrode, an electric motor, speed responsive means connected to said motor for feeding said electrode toward or away from the second electrode, said motor having its armature and one field coil in shunt to the arc and a second coil in series therewith and accumulatively Wound with respect to said shunt coil.

4. In an arc lamp, a pair of cooperating electrodes, an electric motor, means connected to the motor for feeding the electrodes together or apart in accordance with the speed of the motor, said motor having its armature and one field coil in shunt to the arc, and a second coil in series with the arc and accumulatively Wound with respect to said shunt coil.

5. Inan arc lamp, a source of constant potential current, a motor having its armature and a field coil connected across said source and a second coil connected in series therewith and accumulatively wound with respect to said shunt coil, a pair of electrodes and means for feeding said electrodes together or apart in accordance with the speed of the motor. I

In witness whereof, I have hereunto set. my hand this 10th day of .April, 1913.

JOHN L. HALL. Witnesses: BENJAMIN B. HULL, HELEN ORFORD. 

